Update to CDC's Treatment Guidelines for Gonococcal Infection, 2020

Mutations in PBP2 from ceftriaxone-resistant Neisseria gonorrhoeae alter the dynamics of the β3-β4 loop to favor a low-affinity drug-binding state

Resistance to the extended-spectrum cephalosporin ceftriaxone in the pathogenic bacteria Neisseria gonorrhoeae is conferred by mutations in penicillin-binding protein 2 (PBP2), the lethal target of the antibiotic, but how these mutations exert their effect at the molecular level is unclear. Using solution NMR, X-ray crystallography, and isothermal titration calorimetry, we report that WT PBP2 exchanges dynamically between a low-affinity state with an extended β3–β4 loop conformation and a high-affinity state with an inward β3–β4 loop conformation. Histidine-514, which is located at the boundary of the β4 strand, plays an important role during the exchange between these two conformational states. We also find that mutations present in PBP2 from H041, a ceftriaxone-resistant strain of N. gonorrhoeae, increase resistance to ceftriaxone by destabilizing the inward β3–β4 loop conformation or stabilizing the extended β3–β4 loop conformation to favor the low-affinity drug-binding state. These observations reveal a unique mechanism for ceftriaxone resistance, whereby mutations in PBP2 lower the proportion of target molecules in the high-affinity drug-binding state and thus reduce inhibition at lower drug concentrations.

Screening for Chlamydia and Gonorrhea: US Preventive Services Task Force Recommendation Statement

IMPORTANCE

Chlamydia and gonorrhea are among the most common sexually transmitted infections in the US. Infection rates are highest among adolescents and young adults of both sexes. Chlamydial and gonococcal infections in women are usually asymptomatic and may lead to pelvic inflammatory disease and its associated complications. Newborns of pregnant persons with untreated infection may develop neonatal chlamydial pneumonia or gonococcal or chlamydial ophthalmia. Infection in men may lead to urethritis and epididymitis. Both types of infection can increase risk of acquiring or transmitting HIV.

OBJECTIVE

To update its 2014 recommendation, the US Preventive Services Task Force (USPSTF) commissioned a systematic review to evaluate the benefits and harms of screening for chlamydia and gonorrhea in sexually active adolescents and adults, including pregnant persons.

POPULATION

Asymptomatic, sexually active adolescents and adults, including pregnant persons.

EVIDENCE ASSESSMENT

The USPSTF concludes with moderate certainty that screening for chlamydia in all sexually active women 24 years or younger and in women 25 years or older who are at increased risk for infection has moderate net benefit. The USPSTF concludes with moderate certainty that screening for gonorrhea in all sexually active women 24 years or younger and in women 25 years or older who are at increased risk for infection has moderate net benefit. The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for chlamydia and gonorrhea in men.

RECOMMENDATION

The USPSTF recommends screening for chlamydia in all sexually active women 24 years or younger and in women 25 years or older who are at increased risk for infection. (B recommendation) The USPSTF recommends screening for gonorrhea in all sexually active women 24 years or younger and in women 25 years or older who are at increased risk for infection. (B recommendation) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for chlamydia and gonorrhea in men. (I statement).

Challenges in Drug Discovery for Intracellular Bacteria

Novel drugs are needed to treat a variety of persistent diseases caused by intracellular bacterial pathogens. Virulence pathways enable many functions required for the survival of these pathogens, including invasion, nutrient acquisition, and immune evasion. Inhibition of virulence pathways is an established route for drug discovery; however, many challenges remain. Here, we propose the biggest problems that must be solved to advance the field meaningfully. While it is established that we do not yet understand the nature of chemicals capable of permeating into the bacterial cell, this problem is compounded when targeting intracellular bacteria because we are limited to only those chemicals that can permeate through both human and bacterial outer envelopes. Unfortunately, many chemicals that permeate through the outer layers of mammalian cells fail to penetrate the bacterial cytoplasm. Another challenge is the lack of publicly available information on virulence factors. It is virtually impossible to know which virulence factors are clinically relevant and have broad cross-species and cross-strain distribution. In other words, we have yet to identify the best drug targets. Yes, standard genomics databases have much of the information necessary for short-term studies, but the connections with patient outcomes are yet to be established. Without comprehensive data on matters such as these, it is difficult to devise broad-spectrum, effective anti-virulence agents. Furthermore, anti-virulence drug discovery is hindered by the current state of technologies available for experimental investigation. Antimicrobial drug discovery was greatly advanced by the establishment and standardization of broth microdilution assays to measure the effectiveness of antimicrobials. However, the currently available models used for anti-virulence drug discovery are too broad, as they must address varied phenotypes, and too expensive to be generally adopted by many research groups. Therefore, we believe drug discovery against intracellular bacterial pathogens can be advanced significantly by overcoming the above hurdles.

Pelvic inflammatory disease in the adolescent and young adult: An update

Pelvic inflammatory disease (PID) is an infection of the female upper genital tract that is typically polymicrobial with classic core involvement of Neisseria gonorrhoeae and/or Chlamydia trachomatis, though other endogenous flora from the vagino-cervical areas can be involved as well. It is often a sexually transmitted disease but other etiologic routes are also noted. A variety of risk factors have been identified including adolescence, young adulthood, adolescent cervical ectropion, multiple sexual partners, immature immune system, history of previous PID, risky contraceptive practices and others. An early diagnosis and prompt treatment are necessary to reduce risks of PID complications such as chronic pelvic pain, ectopic pregnancy and infertility. Current management principles of PID are also reviewed. It is important for clinicians to screen sexually active females for common sexually transmitted infections such as Chlamydia trachomatis and provide safer sex education to their adolescent and young adult patients. Clinicians should provide comprehensive management to persons with PID and utilize established guidelines such as those from the US Centers for Disease Control and Prevention (CDC).

Adult gonococcal conjunctivitis: Prevalence, clinical features and complications

Introduction. Gonorrhoea is a sexually transmitted disease whose incidence has increased in recent years and adult gonococcal conjunctivitis (AGC) is a relatively uncommon complication.Hypothesis/Gap Statement. AGC is associated with increased incidence of genital gonorrhoea and must be treated correctly to avoid serious corneal complications.Aims. To report the prevalence, clinical features, and complications of AGC in a tertiary ophthalmology centre in Barcelona, Spain. Present epidemiological data, clinical features, ocular complications, and antibiotic susceptibility. Design: Single-centre, descriptive, retrospective case series.Methodology. Systematic case-defined search in medical records and further retrospective chart review study of microbiologically confirmed AGC attending outpatient clinic and/or emergency room from 2012 to 2020. We analysed the clinical presentation, treatments, antibiotic susceptibility, complications and ocular sequelae.Results. Thirteen patients were diagnosed of AGC. Eleven patients had unilateral presentation. Two patients had bilateral presentation. In ten cases there was abundant mucopurulent discharge, three cases presented periocular pain and periocular inflammation requiring a CT scan to rule out post-septal cellulitis. The diagnosis was confirmed by culture. In total, 100 % of strains were susceptible to ceftriaxone, 58 % were ciprofloxacin resistant and no beta-lactamase production was detected. Three patients required hospital admission. One patient developed a complication presenting with ptosis caused by superior symblepharon.Conclusion. AGC is a rare disease which is difficult to diagnose as it requires a high index of suspicion to prevent corneal perforation but in an important number of cases it may mimic orbital cellulitis. It is crucial that treatment starts as soon as possible to avoid serious corneal damage. Patients should promptly receive complete and correct treatment when admitted to the emergency room since an elevated number of patients do not attend their medical follow-up visit. Azithromycin or aminoglycoside eye drops are probably the best option to complete the treatment, due to high quinolone resistance.

Serum Complement Activation by C4BP-IgM Fusion Protein Can Restore Susceptibility to Antibiotics in Neisseria gonorrhoeae

Neisseria gonorrhoeae is the etiological agent of gonorrhea, the second most common bacterial sexually transmitted infection worldwide. Reproductive sequelae of gonorrhea include infertility, ectopic pregnancy and chronic pelvic pain. Most antibiotics currently in clinical use have been rendered ineffective due to the rapid spread of antimicrobial resistance among gonococci. The developmental pipeline of new antibiotics is sparse and novel therapeutic approaches are urgently needed. Previously, we utilized the ability of N. gonorrhoeae to bind the complement inhibitor C4b-binding protein (C4BP) to evade killing by human complement to design a chimeric protein that linked the two N-terminal gonococcal binding domains of C4BP with the Fc domain of IgM. The resulting molecule, C4BP-IgM, enhanced complement-mediated killing of gonococci. Here we show that C4BP-IgM induced membrane perturbation through complement deposition and membrane attack complex pore insertion facilitates the access of antibiotics to their intracellular targets. Consequently, bacteria become more susceptible to killing by antibiotics. Remarkably, C4BP-IgM restored susceptibility to azithromycin of two azithromycin-resistant clinical gonococcal strains because of overexpression of the MtrC-MtrD-MtrE efflux pump. Our data show that complement activation can potentiate activity of antibiotics and suggest a role for C4BP-IgM as an adjuvant for antibiotic treatment of drug-resistant gonorrhea.

Arthritis-Dermatitis Syndrome: a Case of Disseminated Gonococcal Infection with Petechial Skin Rash

A previously healthy 36-year-old woman was admitted to the hospital with vaginal discharge, bilateral ankle pain, and a lower extremity skin rash, all of which developed after unprotected vaginal intercourse with a new male partner. On examination, there was a petechial and purpuric rash involving the lower extremities and bilateral tenosynovitis of the ankle dorsiflexor tendons. Urine NAAT was positive for Neisseria gonorrhea, confirming disseminated gonococcal infection (DGI). The patient was initially treated with oral azithromycin and intravenous ceftriaxone, but as a result of psychosocial circumstances, she was prematurely discharged on an oral cephalosporin agent. She represented with treatment-failure DGI and was treated with a 7-day course of intramuscular ceftriaxone. Repeat urine NAAT was negative for gonorrhea and the patient remained asymptomatic. This case features an atypical cutaneous manifestation of DGI, characterized by a painless petechial and purpuric skin rash rather than the tender papulo-pustular lesions that are typically seen. Additionally, it highlights the importance of DGI treatment with a 7-day parenteral cephalosporin therapy when antibiotic susceptibility is not available.

Treatment efficacy for rectal Neisseria gonorrhoeae: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Rectal gonorrhoea is a common sexually transmitted infection with increasing antimicrobial resistance requiring optimization of available treatments.

OBJECTIVES

This systematic review aimed to assess the efficacy of current treatments, previously trialled treatments and new emerging treatments for rectal Neisseria gonorrhoeae (NG).

METHODS

Online bibliographic databases were search from 1 January 1946 to 14 August 2020. All randomized controlled trials (RCTs) with rectal NG data among participants aged 15 years or above and published in English were included. Random effects meta-analyses were used to estimate overall treatment efficacy, defined as microbiological cure. Sub-group analyses included stratifying by diagnostic assay, by dual versus monotherapy, and by currently recommended treatments (e.g. ceftriaxone ± azithromycin) versus previously trialled but not recommended treatments (e.g. amoxicillin) versus emerging treatments (e.g. zoliflodacin). The study protocol was registered on PROSPERO (CRD42020202998).

RESULTS

54 studies including 1813 participants and 44 treatment regimens were identified. The overall summary treatment efficacy for rectal NG was 100.0% (95% CI: 99.9%-100.0%; I2 = 0.0%; P = 0.86). Efficacy estimates for monotherapies (100.0%; 95% CI: 99.88%-100.0%; I2 = 0.00%; P = 0.97) and dual therapies (100.0%; 95% CI: 97.65%-100.0%; I2 = 56.24%; P = 0.03) were similar. Efficacy was highest for current treatments (100.00%; 95% CI: 99.96%-100.00%; I2 = 0.00%; P = 0.98) versus emerging treatments (97.16%; 95% CI: 86.79%-100.00%; I2 = 0.00%; P = 0.84). There were no trials exclusively investigating rectal NG and small sample size was a limitation in most trials.

CONCLUSIONS

Currently recommended treatments containing ceftriaxone, as mono or dual therapy, are effective. Emerging drugs such as zoliflodacin may be potentially useful for rectal NG but further data are needed.

Genomic Epidemiology of Azithromycin-Nonsusceptible Neisseria gonorrhoeae, Argentina, 2005-2019

Azithromycin-nonsusceptible Neisseria gonorrhoeae strains are an emerging global public health threat. During 2015–2018, the prevalence of azithromycin-nonsusceptible gonococcal infection increased significantly in Argentina. To investigate the genomic epidemiology and resistance mechanisms of these strains, we sequenced 96 nonsusceptible isolates collected in Argentina during 2005–2019. Phylogenomic analysis revealed 2 main clades, which were characterized by a limited geographic distribution, circulating during January 2015–November 2019. These clades included the internationally spreading multilocus sequence types (STs) 1580 and 9363. The ST1580 isolates, which had MICs of 2–4 μg/mL, had mutations in the 23S rRNA. The ST9363 isolates, which had MICs of 2–4 or >256 μg/mL, had mutations in the 23S rRNA, a mosaic mtr locus, or both. Identifying the geographic dissemination and characteristics of these predominant clones will guide public health policies to control the spread of azithromycin-nonsusceptible N. gonorrhoeae in Argentina.

Preclinical Testing of Vaccines and Therapeutics for Gonorrhea in Female Mouse Models of Lower and Upper Reproductive Tract Infection

Murine models of Neisseria gonorrhoeae lower reproductive tract infection are valuable systems for studying N. gonorrhoeae adaptation to the female host and immune responses to infection. These models have also accelerated preclinical testing of candidate therapeutic and prophylactic products against gonorrhea. However, because N. gonorrhoeae infection is restricted to the murine cervicovaginal region, there is a need for an in vivo system for translational work on N. gonorrhoeae pelvic inflammatory disease (PID). Here we discuss the need for well-characterized preclinical upper reproductive tract infection models for developing candidate products against N. gonorrhoeae PID, and report a refinement of the gonorrhea mouse model that supports sustained upper reproductive tract infection. To establish this new model for vaccine testing, we also tested the licensed meningococcal 4CMenB vaccine, which cross-protects against murine N. gonorrhoeae lower reproductive tract infection, for efficacy against N. gonorrhoeae in the endometrium and oviducts following transcervical or vaginal challenge.

Large Increase in Azithromycin-Resistant Neisseria gonorrhoeae in Northern Spain

The aim of this study was to characterize the evolution of gonorrhea in the general population by correlating epidemiological, genotypic, and antimicrobial resistance data of Neisseria gonorrhoeae isolates collected in northern Spain from 2014 to 2018. One hundred ninety-four strains underwent antimicrobial susceptibility testing and were genetically analyzed by N. gonorrhoeae multiantigen sequence typing. Increasing cases of gonococcal infections have been observed after 2015. Most occurred in male with urethritis. Sequence type (ST)-9972 and ST-1576, the predominant genotypes identified, have not been previously described as epidemic clones. Of great concern was the significant increase in azithromycin-resistant N. gonorrhoeae. More than 30% of these isolates were obtained from men who have sex with men (MSM). ST-12302 was the most prevalent clone among the azithromycin-resistant strains, and was also resistant to penicillin, ciprofloxacin, and tetracycline. This multidrug-resistant clone was exclusively isolated from MSM during 2018. The incidence rates of gonorrhea and azithromycin-resistant N. gonorrhoeae have significantly increased due to the emergence of new clones. ST-12302 has recently been recognized as an epidemic clone; therefore, its surveillance could be the key in controlling further dissemination of azithromycin resistance. These data highlight the need to perform local studies to update treatment guidelines and reinforce preventive measures against gonorrhea.

In vitro evaluation of antimicrobial resistance selection in Neisseria gonorrhoeae

Gonococcal infections represent an urgent public-health threat as >50% of cases caused by Neisseria gonorrhoeae strains display reduced susceptibility to at least one antimicrobial agent. We evaluated the pharmacodynamics of a number of antimicrobials against N. gonorrhoeae in order to assess the likelihood of mutant selection by these agents. The mutant prevention concentration (MPC) and mutant selection window (MSW) were determined for azithromycin, ceftriaxone, doxycycline, ertapenem, gentamicin, ciprofloxacin, levofloxacin and moxifloxacin against a wild-type strain of N. gonorrhoeae (ATCC 49226) and a gyrA mutant of ATCC 49226. Pharmacokinetic parameters, including peak concentration (C_max), half-life (t_1/2) and area under the plasma concentration-time curve over 24 h (AUC), associated with each agent were used to calculate the time within the MSW (T_MSW, percentage of the dosing interval that antimicrobial concentrations fall within the MSW), C_max/MPC ratio and AUC/MPC ratio for each antimicrobial agent. Concentrations of ceftriaxone (500 mg), ertapenem, ciprofloxacin, levofloxacin and moxifloxacin surpass the MPC for both strains. Results of pharmacodynamic analyses suggest that ertapenem, ciprofloxacin, levofloxacin and moxifloxacin may be most likely to prevent mutant selection in N. gonorrhoeae. Use of ceftriaxone, azithromycin, doxycycline or gentamicin for gonorrhoea is expected to lead to the ongoing emergence of resistance to these agents. There is a clear need to develop novel treatment regimens for gonococcal infections in order to limit the dissemination of resistance in N. gonorrhoeae.

Genomic Analysis of the Predominant Strains and Antimicrobial Resistance Determinants Within 1479 Neisseria gonorrhoeae Isolates From the US Gonococcal Isolate Surveillance Project in 2018

BACKGROUND

The prevalence of Neisseria gonorrhoeae (GC) isolates with elevated minimum inhibitory concentrations to various antibiotics continues to rise in the United States and globally. Genomic analysis provides a powerful tool for surveillance of circulating strains, antimicrobial resistance determinants, and understanding of transmission through a population.

METHODS

Neisseria gonorrhoeae isolates collected from the US Gonococcal Isolate Surveillance Project in 2018 (n = 1479) were sequenced and characterized. Whole-genome sequencing was used to identify sequence types, antimicrobial resistance profiles, and phylogenetic relationships across demographic and geographic populations.

RESULTS

Genetic characterization identified that (1) 80% of the GC isolates were represented in 33 multilocus sequence types, (2) isolates clustered in 23 major phylogenetic clusters with select phenotypic and demographic prevalence, and (3) common antimicrobial resistance determinants associated with low-level or high-level decreased susceptibility or resistance to relevant antibiotics.

CONCLUSIONS

Characterization of this 2018 Gonococcal Isolate Surveillance Project genomic data set, which is the largest US whole-genome sequence data set to date, sets the basis for future prospective studies, and establishes a genomic baseline of GC populations for local and national monitoring.

Testing as Prevention of Resistance in Bacteria Causing Sexually Transmitted Infections-A Population-Based Model for Germany

Prescribed antibiotic treatments which do not match the therapeutic requirements of potentially co-existing undetected sexually transmitted infections (STIs) can facilitate the selection of antibiotic-drug-resistant clones. To reduce this risk, this modelling assessed the potential applicability of reliable rapid molecular test assays targeting bacterial STI prior to the prescription of antibiotic drugs. The modelling was based on the prevalence of three bacterial STIs in German heterosexual and men-having-sex-with-men (MSM) populations, as well as on reported test characteristics of respective assays. In the case of the application of rapid molecular STI assays for screening, the numbers needed to test in order to correctly identify any of the included bacterial STIs ranged from 103 to 104 for the heterosexual population and from 5 to 14 for the MSM population. The number needed to harm—defined as getting a false negative result for any of the STIs and a false positive signal for another one, potentially leading to an even more inappropriate adaptation of antibiotic therapy than without any STI screening—was at least 208,995 for the heterosexuals and 16,977 for the MSM. Therefore, the screening approach may indeed be suitable to avoid unnecessary selective pressure on bacterial causes of sexually transmitted infections.

Sexually Transmitted Infections Treatment Guidelines, 2021

These guidelines for the treatment of persons who have or are at risk for sexually transmitted infections (STIs) were updated by CDC after consultation with professionals knowledgeable in the field of STIs who met in Atlanta, Georgia, June 11-14, 2019. The information in this report updates the 2015 guidelines. These guidelines discuss 1) updated recommendations for treatment of Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis; 2) addition of metronidazole to the recommended treatment regimen for pelvic inflammatory disease; 3) alternative treatment options for bacterial vaginosis; 4) management of Mycoplasma genitalium; 5) human papillomavirus vaccine recommendations and counseling messages; 6) expanded risk factors for syphilis testing among pregnant women; 7) one-time testing for hepatitis C infection; 8) evaluation of men who have sex with men after sexual assault; and 9) two-step testing for serologic diagnosis of genital herpes simplex virus. Physicians and other health care providers can use these guidelines to assist in prevention and treatment of STIs.

Tackling Antimicrobial Resistance in the Shadow of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic is a challenge for ongoing efforts to combat antimicrobial-resistant (AMR) bacterial infections. As we learn more about COVID-19 disease and drug stewardship evolves, there is likely to be a lasting impact of increased use of antimicrobial agents and antibiotics, as well as a lack of consistent access to health care across many populations. Sexually transmitted infections have been underreported during the pandemic and are often caused by some of the most drug-resistant pathogens. In their recent article in mBio, Parzych et al. (E. M. Parzych, S. Gulati, B. Zheng, M. A. Bah, et al., mBio 12:e00242-21, 2021, https://doi.org/10.1128/mBio.00242-21) focus on protection against Neisseria gonorrhoeae infection via in vivo delivery of an antigonococcal DNA-encoded antibody that has been modified for increased complement activation. Nucleic acid approaches are highly adaptable and could be tremendously beneficial for personalized strategies to combat AMR pathogens.

A portable magnetofluidic platform for detecting sexually transmitted infections and antimicrobial susceptibility

Effective treatment of sexually transmitted infections (STIs) is limited by diagnostics that cannot deliver results rapidly while the patient is still in the clinic. The gold standard methods for identification of STIs are nucleic acid amplification tests (NAATs), which are too expensive for widespread use and have lengthy turnaround times. To address the need for fast and affordable diagnostics, we have developed a portable, rapid, on-cartridge magnetofluidic purification and testing (PROMPT) polymerase chain reaction (PCR) test. We show that it can detect Neisseria gonorrhoeae, the pathogen causing gonorrhea, with simultaneous genotyping of the pathogen for resistance to the antimicrobial drug ciprofloxacin in <15 min. The duplex test was integrated into a low-cost thermoplastic cartridge with automated processing of penile swab samples from patients using magnetic beads. A compact instrument conducted DNA extraction, PCR, and analysis of results while relaying data to the user via a smartphone app. This platform was tested on penile swab samples from sexual health clinics in Baltimore, MD, USA (n = 66) and Kampala, Uganda (n = 151) with an overall sensitivity and specificity of 97.7% (95% CI, 94.7 to 100%) and 97.6% (95% CI, 94.1 to 100%), respectively, for N. gonorrhoeae detection and 100% concordance with culture results for ciprofloxacin resistance. This study paves the way for delivering accessible PCR diagnostics for rapidly detecting STIs at the point of care, helping to guide treatment decisions and combat the rise of antimicrobial resistant pathogens.

Structure-Activity Relationship Studies of Acetazolamide-Based Carbonic Anhydrase Inhibitors with Activity against Neisseria gonorrhoeae

Neisseria gonorrhoeae is an urgent threat to public health in the United States and around the world. Many of the current classes of antibiotics to treat N. gonorrhoeae infection are quickly becoming obsolete due to increased rates of resistance. Thus, there is a critical need for alternative antimicrobial targets and new chemical entities. Our team has repurposed the FDA-approved carbonic anhydrase inhibitor scaffold of acetazolamide to target N. gonorrhoeae and the bacteria's essential carbonic anhydrase, NgCA. This study established both structure-activity and structure-property relationships that contribute to both antimicrobial activity and NgCA activity. This ultimately led to molecules 20 and 23, which displayed minimum inhibitory concentration values as low as 0.25 μg/mL equating to an 8- to 16-fold improvement in antigonococcal activity compared to acetazolamide. These analogues were determined to be bacteriostatic against the pathogen and likely on-target against NgCA. Additionally, they did not exhibit any detrimental effects in cellular toxicity assays against both a human endocervical (End1/E6E7) cell line or colorectal adenocarcinoma cell line (Caco-2) at concentrations up to 128 μg/mL. Taken together, this study presents a class of antigonococcal agents with the potential to be advanced for further evaluation in N. gonorrhoeae infection models.

Challenges in Treating Chlamydia trachomatis, Including Rectal Infections: Is It Time to Go Back to Doxycycline?

OBJECTIVE

To evaluate recent publications on efficacy of single-dose azithromycin and 7-day doxycycline when treating Chlamydia trachomatis.

DATA SOURCES

A literature search of MEDLINE, EMBASE, PubMed, and Cochrane library was conducted (1990 to June 13, 2021) using the terms: Chlamydia trachomatis, genital chlamydia, rectal chlamydia, extragenital chlamydia, azithromycin, doxycycline, and treatment guidelines. ClinicalTrials.gov was searched to identify ongoing trials.

STUDY SELECTION AND DATA EXTRACTION

English language studies, including controlled studies, retrospective analyses, systematic reviews, meta-analyses, and case reports, reporting microbiological or clinical outcomes in adolescents and adults were considered.

DATA SYNTHESIS

Systemic reviews and meta-analyses of randomized trials reported azithromycin efficacy of 96% to 97% in genital chlamydia. However, reports of treatment failure have emerged, especially among symptomatic males, with an increased risk of microbiological failure after azithromycin than doxycycline (relative risk = 2.45; 95% CI = 1.36-4.41). Retrospective analyses and prospective observational cohort studies reported lower efficacy range following azithromycin than doxycycline (74%-87% vs 92%-100%, respectively) in rectal chlamydia. First randomized controlled trial comparing azithromycin and doxycycline reported significantly higher microbiological cure following doxycycline, with absolute difference of 26% (95% CI = 16%-36%; P < 0.001). The proposed 2021 Centers for Disease Control and Prevention treatment guidelines designate doxycycline as the preferred agent for treatment at any site.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

A growing body of evidence for treatment failure following azithromycin, especially in rectal chlamydia supports updating current practice.

CONCLUSIONS

Doxycycline continues to achieve high efficacy in genital and rectal chlamydia. Clinicians should consider efficacy with convenience of dosing regimen, medication compliance, and sexual behavior risks when treating chlamydia infections.

Epidemiology, Treatments, and Vaccine Development for Antimicrobial-Resistant Neisseria gonorrhoeae: Current Strategies and Future Directions

Neisseria gonorrhoeae is the second most common bacterial sexually transmitted infection in the world after Chlamydia trachomatis. The pathogen has developed resistance to every antibiotic currently approved for treatment, and multidrug-resistant strains have been identified globally. The current treatment recommended by the World Health Organization is ceftriaxone and azithromycin dual therapy. However, resistance to azithromycin and ceftriaxone are increasing and treatment failures have been reported. As a result, there is a critical need to develop novel strategies for mitigating the spread of antimicrobial-resistant N. gonorrhoeae through improved diagnosis and treatment of resistant infections. Strategies that are currently being pursued include developing molecular assays to predict resistance, utilizing higher doses of ceftriaxone, repurposing older antibiotics, and developing newer agents. In addition, efforts to discover a vaccine for N. gonorrhoeae have been reignited in recent years with the cross-protectivity provided by the N. meningitidis vaccine, with several new strategies and targets. Despite the significant progress that has been made, there is still much work ahead to combat antimicrobial-resistant N. gonorrhoeae globally.

Phylogenomic analysis reveals persistence of gonococcal strains with reduced-susceptibility to extended-spectrum cephalosporins and mosaic penA-34

The recent emergence of strains of Neisseria gonorrhoeae associated with treatment failures to ceftriaxone, the foundation of current treatment options, has raised concerns over a future of untreatable gonorrhea. Current global data on gonococcal strains suggest that several lineages, predominately characterized by mosaic penA alleles, are associated with elevated minimum inhibitory concentrations (MICs) to extended spectrum cephalosporins (ESCs). Here we report on whole genome sequences of 813 N. gonorrhoeae isolates collected through the Gonococcal Isolate Surveillance Project in the United States. Phylogenomic analysis revealed that one persisting lineage (Clade A, multi-locus sequence type [MLST] ST1901) with mosaic penA-34 alleles, contained the majority of isolates with elevated MICs to ESCs. We provide evidence that an ancestor to the globally circulating MLST ST1901 clones potentially emerged around the early to mid-20th century (1944, credibility intervals [CI]: 1935-1953), predating the introduction of cephalosporins, but coinciding with the use of penicillin. Such results indicate that drugs with novel mechanisms of action are needed as these strains continue to persist and disseminate globally.

Antigonococcal Activity of (+)-Medicarpin

Antibiotics are the primary drugs for combating Neisseria gonorrhoeae infections, but with evolving antibiotic resistance of this bacterium, new druggable molecules are needed to stem the tide of this impending public health crisis. Propolis has long been recognized for its antimicrobial properties, being composed of secondary metabolites with antibacterial potential. We herein describe the evaluation of a Jamaican multifloral propolis for antibacterial activity against N. gonorrhoeae. The bioassay-guided evaluation of the ethyl acetate extract yielded (+)-medicarpin (1), whose final structure was elucidated based on spectral analysis and comparison with the known metabolites. Compound (1) selectively inhibited N. gonorrhoeae with a minimum inhibitory concentration value of 0.25 mg/mL, showing an additive effect against N. gonorrhoeae when combined with vancomycin.

Antimicrobial resistance and molecular epidemiological typing of Neisseria gonorrhoeae isolates from Kyrgyzstan in Central Asia, 2012 and 2017

Background

Gonorrhoea and antimicrobial resistance (AMR) in Neisseria gonorrhoeae are significant public health concerns globally. Nearly no gonococcal AMR data are available from Central Asia, and no data from Kyrgyzstan has been published. We examined, for the first time, AMR and molecular epidemiology of N. gonorrhoeae isolates cultured in Kyrgyzstan in 2012 and 2017, in order to inform refinements of the Kyrgyz national gonorrhoea management guidelines.

Methods

N. gonorrhoeae isolates cultured in 2012 (n = 84) and 2017 (n = 72) in Kyrgyzstan were examined. MICs of nine antimicrobials were determined using Etest and, where available, clinical breakpoints from the EUCAST were applied. N. gonorrhoeae multiantigen sequence typing (NG-MAST) was also performed.

Results

The overall resistance levels were high to ciprofloxacin (88.5%), tetracycline (56.9%), benzylpenicillin (39.1%), and kanamycin (4.7%). Resistance to cefixime (0.6%, n = 1 isolate), azithromycin (0.6%, n = 1), and gentamicin (0.6%, n = 1) was rare. No resistance to ceftriaxone or spectinomycin was found. However, the proportion of isolates with decreased susceptibility (MIC = 0.125 mg/L) to ceftriaxone and cefixime was 12.8 and 11.5%, respectively. Gonococcal isolates were assigned 69 sequence types, of which 52 (75.4%) were new.

Conclusions

The gonococcal population in Kyrgyzstan in 2012 and 2017 showed a high genetic diversity. Ceftriaxone, 500–1000 mg, in combination with azithromycin 2 g or doxycycline, particularly when chlamydial infection has not been excluded, should be recommended as empiric first-line treatment. Spectinomycin 2 g could be an alternative treatment, and given with azithromycin 2 g if pharyngeal gonorrhoea has not been excluded. Fluoroquinolones, aminoglycosides, benzylpenicillin, or tetracyclines should not be used for empiric treatment of gonorrhoea in Kyrgyzstan. Timely updating and high compliance to national gonorrhoea treatment guidelines based on quality-assured AMR data is imperative. Expanded and improved gonococcal AMR surveillance in Kyrgyzstan is crucial.

Evidence of Horizontal Gene Transfer of 50S Ribosomal Genes rplB, rplD, and rplY in Neisseria gonorrhoeae

Horizontal gene transfer (HGT) in the penA and multidrug efflux pump genes has been shown to play a key role in the genesis of antimicrobial resistance in Neisseria gonorrhoeae. In this study, we evaluated if there was evidence of HGT in the genes coding for the ribosomal proteins in the Neisseria genus. We did this in a collection of 11,659 isolates of Neisseria, including N. gonorrhoeae and commensal Neisseria species (N. cinerea, N. elongata, N. flavescens, N. mucosa, N. polysaccharea, and N. subflava). Comparative genomic analyses identified HGT events in three genes: rplB, rplD, and rplY coding for ribosomal proteins L2, L4 and L25, respectively. Recombination events were predicted in N. gonorrhoeae and N. cinerea, N. subflava, and N. lactamica were identified as likely progenitors. In total, 2,337, 2,355, and 1,127 isolates possessed L2, L4, and L25 HGT events. Strong associations were found between HGT in L2/L4 and the C2597T 23S rRNA mutation that confers reduced susceptibility to macrolides. Whilst previous studies have found evidence of HGT of entire genes coding for ribosomal proteins in other bacterial species, this is the first study to find evidence of HGT-mediated chimerization of ribosomal proteins.

Antimicrobial resistance in Neisseria gonorrhoeae isolates and gonorrhoea treatment in the Republic of Belarus, Eastern Europe, 2009-2019

Background

Limited antimicrobial resistance (AMR) data for Neisseria gonorrhoeae are available in Eastern Europe. We investigated AMR in N. gonorrhoeae isolates in the Republic of Belarus from 2009 to 2019, antimicrobial treatment recommended nationally, and treatment given to patients with gonorrhoea.

Methods

N. gonorrhoeae isolates (n = 522) cultured in three regions of Belarus in 2009–2019 were examined. Determination of minimum inhibitory concentrations (MICs) of eight antimicrobials was performed using Etest. Resistance breakpoints from the European Committee on Antimicrobial Susceptibility Testing were applied where available. A Nitrocefin test identified β-lactamase production. Gonorrhoea treatment for 1652 patients was also analysed. Statistical significance was determined by the Z-test, Fisher’s exact test, or Mann-Whitney U test with p-values of < 0.05 indicating significance.

Results

In total, 27.8% of the N. gonorrhoeae isolates were resistant to tetracycline, 24.7% to ciprofloxacin, 7.0% to benzylpenicillin, 2.7% to cefixime, and 0.8% to azithromycin. No isolates were resistant to ceftriaxone, spectinomycin, or gentamicin. However, 14 (2.7%) isolates had a ceftriaxone MIC of 0.125 mg/L, exactly at the resistance breakpoint (MIC > 0.125 mg/L). Only one (0.2%) isolate, from 2013, produced β-lactamase. From 2009 to 2019, the levels of resistance to ciprofloxacin and tetracycline were relatively high and stable. Resistance to cefixime was not identified before 2013 but peaked at 22.2% in 2017. Only sporadic isolates with resistance to azithromycin were found in 2009 (n = 1), 2012 (n = 1), and 2018–2019 (n = 2). Overall, 862 (52.2%) patients received first-line treatment according to national guidelines (ceftriaxone 1 g). However, 154 (9.3%) patients received a nationally recommended alternative treatment (cefixime 400 mg or ofloxacin 400 mg), and 636 (38.5%) were given non-recommended treatment.

Conclusions

The gonococcal resistance to ciprofloxacin and tetracycline was high, however, the resistance to azithromycin was low and no resistance to ceftriaxone was identified. Ceftriaxone 1 g can continuously be recommended as empiric first-line gonorrhoea therapy in Belarus. Fluoroquinolones should not be prescribed for treatment if susceptibility has not been confirmed by testing. Timely updating and high compliance with national evidence-based gonorrhoea treatment guidelines based on quality-assured AMR data are imperative. The need for continued, improved and enhanced surveillance of gonococcal AMR in Belarus is evident.

Antibiotic Selection for Suspected Neisseria gonorrhoeae Infection Among Penicillin-Allergic Patients in the Emergency Department

Objectives

While penicillin allergies are commonly reported, their cross-reactivity with beta-lactam antibiotics is minimal. First-line treatment of gonorrheal infections includes a cephalosporin. In emergency department (ED) environments, physicians must consider these potential allergies when selecting antibiotics for a patient with symptoms concerning for sexually transmitted infection (STI).

Methods

A retrospective chart review of adult patients with symptoms concerning for STI presenting to an urban ED from January 2014 through June 2019 was performed. Chart discovery used search terms of “STI”, “STD”, “urethritis”, “vaginitis”, and “gonorrhea”. Information abstracted included patient symptoms, type of care provider, antibiotics prescribed or administered in the ED.

Results

A total of 603 patients met inclusion criteria, of which 31 reported allergies to penicillin antibiotics, and another three reported allergies to cephalosporins. Patients reporting penicillin allergy were less likely to receive a cephalosporin antibiotic (p=0.0081). Patients reporting a non-anaphylactic allergy to penicillin received a cephalosporin at a rate of 92.3%. Patients reporting a penicillin allergy under the care of only an attending physician were less likely to receive a cephalosporin antibiotic compared with those whose care teams included either a resident physician or physician assistant (p=0.00019). Patients reporting a penicillin allergy were more likely to receive alternative antibiotics beyond cephalosporins or azithromycin (p=0.048); the most frequently given additional antibiotics were metronidazole, doxycycline, and levofloxacin.

Conclusions 

Patients with penicillin allergies represent a recurring challenge for ED physicians when faced with antibiotic selection for STI symptoms concerning for gonorrheal infection. Those with penicillin allergies are significantly less likely to receive a cephalosporin antibiotic, though these remain the only universally accepted treatment for gonorrheal infections. These findings highlight the significant need for further physician and public education on allergies and antibiotic selection.

Efficacy of 1g ceftriaxone monotherapy compared to dual therapy with azithromycin or doxycycline for treating extragenital gonorrhea among men who have sex with men

BACKGROUND

Evidence on efficacy of high-dose ceftriaxone monotherapy for extragenital Neisseria gonorrhoeae (NG) infection is lacking.

METHODS

A cohort of men who have sex with men (MSM) were tested for NG/Chlamydia trachomatis (CT) every three months, in a single-center observational study in Tokyo, Japan. MSM aged > 19 years diagnosed with extragenital NG infection between 2017 and 2020 were included. A single dose of 1 g ceftriaxone monotherapy was provided, while dual therapy with a single oral dose of 1 g azithromycin or 100 mg doxycycline administered orally twice daily for seven days were given, for those co-infected with CT, according to infected sites. Efficacy of these treatments was calculated by the number of NG-negative subjects at test-of-cure divided by the number of subjects treated. Fisher's exact tests were used to compare the efficacy between the two groups.

RESULTS

Of 320 cases diagnosed with extragenital NG, 208 were treated with monotherapy and 112 were treated with dual therapy. The efficacy against total, pharyngeal, and rectal infections was 98.1% (204/208, 95% Confidence Interval (CI): 95.2-99.3%), 97.8% (135/138, 95% CI: 93.8-99.4%), and 98.6% (69/70, 95% CI: 92.3-99.9%), respectively, in the monotherapy group, while the corresponding efficacy in the dual therapy was 95.5% (107/112, 95% CI: 90.0-98.1%), 96.1% (49/51, 95% CI: 86.8-99.3%) and 95.1% (58/61, 95% CI: 86.5-98.7%), respectively. No significant difference in the corresponding efficacy was observed between the two groups (p=0.29, p=0.61, p=0.34, respectively).

CONCLUSIONS

High-dose ceftriaxone monotherapy is as effective as dual therapy for extragenital NG among MSM.

Molecular characterization of decreased susceptibility to ceftriaxone and genotyping of Neisseria gonorrheae isolates in New Delhi, India

Data on genetic characteristics of Neisseria gonorrhoeae isolates exhibiting decreased susceptibility to extended-spectrum cephalosporins in India is deficient. In this study, we have sequenced penA, porB, mtrR and ponA and bla_TEM genes in 70 clinical isolates of NG with varying ceftriaxone MICs. Amongst these, 22 (31.4%) were PPNG. Additionally, N. gonorrheae Multiantigen Sequence Typing was performed. Fisher exact and χ² were used to evaluate significance of mutations with MICs. A total of six non-mosaic penA (Penicillin binding protein 2 [PBP2]) amino acid patterns were seen (II, IV, IX, XII, XIX, XXII) of which, pattern IX was significantly associated with decreased susceptibility to ceftriaxone. Other significant associations were noted in porB & mtrR genes. There were no mutations in bla_TEM gene. ST6069 was significantly associated with decreased susceptibility to ceftriaxone. To conclude, development of decreased susceptibility to ceftriaxone in gonococci involves cumulation of different mutations in the four chromosomal genes investigated.

Understanding the most commonly billed diagnoses in primary care: Acute pharyngitis

ABSTRACT

This is a 12-part series on the most commonly billed diagnoses in primary care. The article discusses the pathophysiologic processes of acute pharyngitis as well as the clinical manifestations and treatments and how they are linked to disease pathogenesis.

Choosing New Therapies for Gonorrhoea: We Need to Consider the Impact on the Pan-Neisseria Genome. A Viewpoint

The development of new gonorrhoea treatment guidelines typically considers the resistance-inducing effect of the treatment only on Neisseria gonorrhoeae. Antimicrobial resistance in N. gonorrhoeae has, however, frequently first emerged in commensal Neisseria species and then been passed on to N. gonorrhoeae via transformation. This creates the rationale for considering the effect of gonococcal therapies on resistance in commensal Neisseria. We illustrate the benefits of this pan-Neisseria strategy by evaluating three contemporary treatment options for N. gonorrhoeae-ceftriaxone plus azithromycin, monotherapy with ceftriaxone and zoliflodacin.

Typing of Neisseria Gonorrhoeae isolates in Shenzhen, China from 2014-2018 reveals the shift of genotypes associated with antimicrobial resistance

The growing antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a serious global threat to gonococcal therapy. Molecular typing is an ideal tool to reveal the association between specific genotype and resistance phenotype that provides effective data for tracking the transmission of resistant clones of N. gonorrhoeae In our study, we aimed to describe the molecular epidemiology of AMR and the distribution of resistance-associated genotypes in Shenzhen during 2014-2018. In total, 909 isolates were collected from Shenzhen from 2014-2018. Two typing schemes, multilocus sequence typing (MLST) and N. gonorrhoeae Sequence Typing for Antimicrobial Resistance (NG-STAR), were performed for all isolates. The distribution of resistance-associated genotypes was described using goeBURST analysis combined with data of logistic regression. Among 909 isolates, ST₈₁₂₃, ST₇₃₆₃, ST₁₉₀₁, ST₇₃₆₅, and ST₇₃₆₀ were most the common MLST sequence types (STs), and ST₃₄₈, ST₂₄₇₃, ST₄₉₇, and ST₁₉₉ were the most prevalent NG-STAR STs. The logistic regression analysis showed that NG-STAR_ST497, MLST_ST7365, and MLST_ST7360 were typically associated with decreased susceptibility to ceftriaxone. Furthermore, the internationally spreading ESC-resistant clone MLST_ST1901 has been prevalent at least in 2014 in Shenzhen and showed a significant increase during 2014-2018. Additionally, MLST_ST7363 owns the potential to become the next internationally spreading ceftriaxone-resistant ST. In conclusions, we performed a comprehensive epidemiological study to explore the correlation between AMR and specific STs, which provided important data for future studies of the molecular epidemiology of AMR in N. gonorrhoeae Besides, these findings provide insight for adjusting surveillance strategies and therapy management in Shenzhen.

Estimates of the Prevalence and Incidence of Chlamydia and Gonorrhea Among US Men and Women, 2018

BACKGROUND

The most recent prevalence and incidence estimates for chlamydia and gonorrhea, the 2 most reported sexually transmitted infections in the United States, were for 2008. We present updated estimates of the number of prevalent and incident chlamydial and gonococcal infections for 2018.

METHODS

We estimated chlamydial prevalence directly from the 2015 to 2018 cycles of the National Health and Nutrition Examination Survey and chlamydial incidence using a mathematical model primarily informed by National Health and Nutrition Examination Survey and case report data. Total and antimicrobial-resistant gonococcal prevalence and incidence were estimated using mathematical models primarily informed by case report and Gonococcal Isolate Surveillance Program data. Estimates were calculated for the total population, all women, and all men aged 15 to 39 years, stratified by age group. Primary estimates represent medians and uncertainty intervals represent the 25th (Q1) and 75th (Q3) percentiles of the empirical frequency distributions of prevalence and incidence for each infection.

RESULTS

Among persons aged 15 to 39 years in the United States in 2018, we estimate 2.35 (Q1, 2.20; Q3, 2.51) million prevalent and 3.98 (Q1, 3.77; Q3, 4.22) million incident chlamydial infections, and an estimated 209,000 (Q1, 183,000; Q3, 241,000) prevalent and 1.57 (Q1, 1.44; Q3, 1.72) million incident gonococcal infections. Of all gonococcal infections, there were 107,000 (Q1, 94,000; Q3, 124,000) prevalent and 804,000 (Q1, 738,000; Q3, 883,000) incident infections demonstrating antimicrobial resistance or elevated minimum inhibitory concentrations to selected antibiotics.

CONCLUSIONS

Chlamydia and gonorrhea were very common in the United States in 2018. Estimates show that more than 800,000 newly acquired gonococcal infections in 2018 demonstrated resistance or elevated minimum inhibitory concentrations to currently or previously recommended antibiotics.

Reduction in antibiotic prescribing attainable with a gonococcal vaccine

We estimated the fraction of antibiotic prescribing in the United States attributable to gonorrhea. Gonorrhea contributes to an outsized proportion of antibiotic prescriptions in young adults, males, and in the southern and western United States. A gonococcal vaccine could substantially reduce antibiotic prescribing in these populations.

Associations between antimicrobial susceptibility/resistance of Neisseria gonorrhoeae isolates in European Union/European Economic Area and patients' gender, sexual orientation and anatomical site of infection, 2009-2016

BACKGROUND

The emergence and spread of antimicrobial resistance (AMR) in Neisseria gonorrhoeae, nationally and internationally, is a serious threat to the management and control of gonorrhoea. Limited and conflicting data regarding the epidemiological drivers of gonococcal AMR internationally have been published. We examined the antimicrobial susceptibility/resistance of gonococcal isolates (n = 15,803) collected across 27 European Union/European Economic Area (EU/EEA) countries in 2009-2016, in conjunction to epidemiological and clinical data of the corresponding patients, to elucidate associations between antimicrobial susceptibility/resistance and patients' gender, sexual orientation and anatomical site of infection.

METHODS

In total, 15,803 N. gonorrhoeae isolates from the European Gonococcal Antimicrobial Surveillance Programme (Euro-GASP), 2009-2016, were examined. Associations between gonococcal susceptibility/resistance and patients' gender, sexual orientation and anatomical site of infection were investigated using univariate and multivariate logistic regression analysis. Statistical significance was determined by Pearson χ2-test or Fisher's exact test with two-tailed p-values of < 0.05 indicating significance.

RESULTS

The overall gonococcal resistance from 2009 to 2016 was 51.7% (range during the years: 46.5-63.5%), 7.1% (4.5-13.2%), 4.3% (1.8-8.7%), and 0.2% (0.0-0.5%) to ciprofloxacin, azithromycin, cefixime, and ceftriaxone, respectively. The level of resistance combined with decreased susceptibility to ceftriaxone was 10.2% (5.7-15.5%). Resistance to cefixime and ciprofloxacin, and resistance combined with decreased susceptibility to ceftriaxone were positively associated with urogenital infections and heterosexual males, males with sexual orientation not reported and females (except for ciprofloxacin), i.e. when compared to men-who-have-sex-with-men (MSM). Azithromycin resistance was positively associated with heterosexual males, but no association was significant regarding anatomical site of infection.

CONCLUSIONS

Overall, sexual orientation was the main variable associated with gonococcal AMR. Strongest positive associations were identified with heterosexual patients, particularly males, and not MSM. To provide evidence-based understanding and mitigate gonococcal AMR emergence and spread, associations between antimicrobial susceptibility/resistance and patients' gender, sexual orientation and anatomical site of infection need to be further investigated in different geographic settings. In general, these insights will support identification of groups at increased risk and targeted public health actions such as intensified screening, 3-site testing using molecular diagnostics, sexual contact tracing, and surveillance of treatment failures.

Susceptibility Trends of Zoliflodacin against Multidrug-Resistant Neisseria gonorrhoeae Clinical Isolates in Nanjing, China, 2014 to 2018

Previously, we reported the potent activity of a novel spiropyrimidinetrione, zoliflodacin, against Neisseria gonorrhoeae isolates collected in 2013 from symptomatic men in Nanjing, China. Here, we investigated trends of susceptibilities to zoliflodacin in 986 isolates collected from men between 2014 and 2018. N. gonorrhoeae isolates were tested for susceptibility to zoliflodacin and seven other antibiotics. Mutations in the gyrA, gyrB, parC, parE, and mtrR genes were determined by PCR and sequencing. The MICs of zoliflodacin ranged from ≤0.002 to 0.25 mg/liter; the overall MIC50 and MIC90 were 0.06 mg/liter and 0.125 mg/liter, respectively, in 2018, increasing 2-fold from 2014. However, the percentage of isolates with lower zoliflodacin MICs declined in each year sequentially, while the percentage with higher MICs increased yearly (P ≤ 0.00001). All isolates were susceptible to spectinomycin but resistant to ciprofloxacin (MIC ≥ 1 mg/liter); 21.2% (209/986) were resistant to azithromycin (≥1 mg/liter), 43.4% (428/986) were penicillinase-producing N. gonorrhoeae (PPNG), 26.9% (265/986) were tetracycline-resistant N. gonorrhoeae (TRNG), and 19.4% (191/986) were multidrug-resistant (MDR) isolates. 202 isolates with the lowest (≤0.002 to 0.015 mg/liter) and highest (0.125 to 0.25 mg/liter) zoliflodacin MICs were quinolone resistant with double or triple mutations in gyrA; 193/202 (95.5%) also had mutations in parC There were no D429N/A and/or K450T mutations in GyrB identified in the 143 isolates with higher zoliflodacin MICs; an S467N mutation in GyrB was identified in one isolate. We report that zoliflodacin continues to have excellent in vitro activity against clinical gonococcal isolates, including those with high-level resistance to ciprofloxacin, azithromycin, and extended-spectrum cephalosporins.

Cyr SB, Pham CD, Kirkcaldy RD. Sustained Transmission of Neisseria gonorrhoeae with High-Level Resistance to Azithromycin, in Indianapolis, Indiana, 2017–2018

Background

Since 2014, Neisseria gonorrhoeae azithromycin (AZM) susceptibility has declined in the United States, but high-level AZM resistance (HL-AZMR) has been infrequent and sporadic. We describe a cluster of 14 N. gonorrhoeae isolates with HL-AZMR identified in Indianapolis over 13 months.

Methods

N. gonorrhoeae culture specimens (genital and extragenital) were collected from attendees of the Bell Flower Clinic. Isolates underwent antimicrobial susceptibility testing (AST) using Etest. AZM minimum inhibitory concentrations ≥256 µg/mL were classified as HL-AZMR. Local disease intervention specialists interviewed patients whose isolates demonstrated HL-AZMR and conducted partner services. Relatedness of isolates was investigated by genomic analyses.

Results

During 2017–2018, AST was performed in 1016 N. gonorrhoeae isolates collected at the Bell Flower Clinic. Fourteen isolates (1.4%) from 12 men collected over 13 months demonstrated HL-AZMR; all were cephalosporin susceptible. Of the 12 men, 9 were white and reported male sex partners. Nine of the men were able to be retested; all were cured with 250-mg ceftriaxone plus 1-g AZM. Two men named each other as partners; no other partners in common were reported. Genomic analysis demonstrated close relatedness of the HL-AZMR isolates and a novel combination of a mosaic-mtrR promoter along with 23S ribosomal RNA mutations that appear to have emerged from circulating strains.

Conclusions

The close genetic relatedness with limited epidemiologic linkages between patients highlights the challenges of gonorrhea partner investigations and suggests undetected local transmission. Local AST, rapid public health action, and epidemiologic investigations combined with genomic analysis provides a multipronged approach to understanding an outbreak of sexually transmitted disease.

Molecular Features of Cephalosporins Important for Activity against Antimicrobial-Resistant Neisseria gonorrhoeae

The increasing prevalence of Neisseria gonorrhoeae strains exhibiting decreased susceptibility to extended-spectrum cephalosporins (ESCs) presents a challenge for the successful treatment of gonorrhea infections. To address this challenge, we evaluated a panel of 23 cephalosporins against penicillin-binding protein 2 (PBP2) from the ESC-resistant (ESC^R) N. gonorrhoeae strain H041 to determine which molecular features are important for antimicrobial activity. Structure-activity relationships (SARs) developed from acylation rate constants against PBP2 and antimicrobial susceptibilities against the H041 strain of N. gonorrhoeae, and interpreted against docking models, reveal that cephalosporins possessing large, lipophilic R₁ side chains and electronegative R₂ side chains with planar groups are associated with higher acylation rates against PBP2, but also that these same amphipathic features can lower antimicrobial activity. Based on these studies, we tested cefoperazone, one of the most effective ESCs for targeting PBP2, in the female mouse model infected with H041 and showed that it was equally or more effective than ceftriaxone or gentamicin for clearing infections. Taken together, our results reveal that two U.S. Food and Drug Administration (FDA)-approved agents (cefoperazone, ceftaroline) and one FDA-qualified infectious disease product (ceftobiprole) have potential as first-line treatments for gonorrhea and provide a framework for the future design of cephalosporins with improved activity against ESC-resistant N. gonorrhoeae.

Comprehensive Bioinformatic Assessments of the Variability of Neisseria gonorrhoeae Vaccine Candidates

A protective vaccine is the only viable way to stop the spread of gonorrhea in the face of rising antibiotic resistance. However, the notorious phase and antigenic variation of Neisseria gonorrhoeae surface proteins remains one of the challenges in vaccine development. To facilitate vaccine advancement efforts, we carried out comprehensive bioinformatic analyses of sequence variation by comparing 34 gonorrhea antigen candidates among >5,000 clinical N. gonorrhoeae isolates deposited in the Neisseria PubMLST database. Eight protein antigens showed exceptional conservation by having a single allele variant distributed in >80% of isolates. An additional 18 vaccine candidates were represented by ≤3 alleles in >50% of N. gonorrhoeae isolates globally. Phylogenetic analyses highlighted closely related antigen variants and additionally showed that AniA and FetB were the closest between N. gonorrhoeae and N. meningitidis Up to 44% of N. meningitidis alleles for both antigens have premature stop codons, suggesting differential expression. Mapping polymorphisms to the available three-dimensional structures of 12 antigens revealed low-frequency surface polymorphisms. PorB and TbpB possessed numerous high-prevalence polymorphic sites. While TbpA was also highly variable, conserved loops were nonetheless identified. A high degree of sequence conservation, the distribution of a single antigen variant among N. gonorrhoeae strains globally, or low-frequency sequence polymorphisms in surface loops make ACP, AniA, BamA, BamE, MtrE, NspA, NGO0778, NGO1251, NGO1985, OpcA, PldA, Slam2, and ZnuD promising candidates for a gonorrhea vaccine. Finally, the commonly used N. gonorrhoeae FA1090 strain emerges as a vaccine prototype, as it carries antigen sequence types identical to the most broadly distributed antigen variants.IMPORTANCE Neisseria gonorrhoeae, the Gram-negative bacterium responsible for the sexually transmitted infection gonorrhea, is categorized as a high-priority pathogen for research and development efforts. N. gonorrhoeae's "superbug" status, its high morbidity, and the serious health impact associated with gonorrhea highlight the importance of vaccine development. One of the longstanding barriers to developing an effective vaccine against N. gonorrhoeae is the remarkable variability of surface-exposed antigens. In this report, we addressed this roadblock by applying extensive bioinformatic analyses to 34 gonorrhea antigen candidates among >5,000 clinical N. gonorrhoeae isolates. Our studies are important, as they reveal promising, conserved gonorrhea vaccine candidates and aid structural vaccinology. Moreover, these approaches are broadly applicable to other infectious diseases where surface antigen variability impedes successful vaccine design.